[asterisk-dev] device_state distribution issues

[Russell Bryant]

On Tue, 2010-11-09 at 11:14 +0100, Klaus Darilion wrote:
> btw: has someone ever did any performance measuring of devicestate 
> distribution? I would suspect ais to have much better performance as it 
> avoids the additional hop of the XMPP server, avoids XML 
> encoding/parsing and is sent by multicast (good for multiple servers as 
> it avoids the sequential XMPP ntofications). Thus, for LAN environments 
> I think ais is much better suited than XMPP.
> 
> So, what is now the purpose of res_ais vs. res_jabber?
> 
> I think the goal of device state distribution with XMPP is to have 
> synchronize the device state over between geographically distributed 
> servers (e.g. main office and branch offices) not for having multiple 
> Asterisk servers for load balancing.
> 
> AIS based state distribution seems very lightweight. Thus, in high 
> traffic environments where a single server can not handle all the load 
> (lots of idle traffic due to REGISTER and OPTIONS, transcoding ...) it 
> allows you to have an Asterisk cluster with one aggregated device state 
> for each device over the whole cluster. Of course at some point if there 
> are many nodes and too many state changes then the cluster may collapse 
> due to the immense ais traffic, but I think state changes are usually 
> not that much (mostly only when a call is created and hangup) compared 
> to other load (RTP, idle traffic) and so I think a cluster of 10 servers 
> or more should not be a problem.
> 
> So, do my comments make sense?

I have not done a performance comparison, but I agree with your
comments.  That is why I think it makes sense to keep both in the tree,
even though they provide the same functionality.

-- 
Russell Bryant
Digium, Inc.  |  Engineering Manager, Open Source Software
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